Astronomers have for the first time seen part of the "cosmic web" of galaxies that holds together the known universe, some seven billion light-years from Earth.
Viewed through the world's most powerful telescopes, the discovery "is the first observation of such a prominent galaxy structure in the distant universe, providing further insight into the cosmic web and how it formed," according to a statement by the European Southern Observatory (ESO).
The assembly of galaxies form filaments "millions of light years long and constitute the skeleton of the universe," it says.
"Galaxies gather around them, and immense galaxy clusters form at their intersections, lurking like giant spiders waiting for more matter to digest," it adds.
The filaments are located about 6.7 billion light-years away and extend over at least 60 million light-years, the scientists say, adding the structure very likely stretches beyond the area they probed, warranting further observations.
"This is the first time that we have observed such a rich and prominent structure in the distant universe," says ESO's Masayuki Tanaka, who led the study.
"We can now move from demography to sociology and study how the properties of galaxies depend on their environment, at a time when the universe was only two thirds of its present age," says Tanaka.
Scientists have long theorized that galaxy clusters are not evenly distributed throughout the universe.
"The most widely accepted cosmological theories predict that matter also clumps on a larger scale in the so-called "cosmic web," in which galaxies, embedded in filaments stretching between voids, create a gigantic wispy structure," says Tanaka.
ESO says the discovery was "made possible by combining two of the most powerful ground-based telescopes in the world", the Very Large Telescope at Chile's Paranal Observatory and the National Astronomical Observatory's Subaru Telescope in Japan.